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B and S lawmower won't start


carolinaman's Avatar
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07-09-07, 07:55 PM   #1  
B and S lawmower won't start

I'm new to the forum and know little of small engines. My push mower has been sputtering like it needs adjusting and just recently would not start at all. It had been starting and running a few seconds if you would push the priming button and then cut off. I did check for spark and there is a spark as I did replace plug with resistor plug. I pulled the bowl off and no objects/water there. I did drain all the old gas and used new gas after the fact. I am assuming I have a carb/fuel problem. Float moves freely and appears no hole in it. There is a small amount of gas I can see in carb when I push prime button which I have now broken at screw so will have to get a new one. I sprayed carb cleaner but everything looks ok. I hate to take to a shop and since it's already broken don't feel like I have a lot to lose anyway. Just looking for some direction on what to do next. This is a Briggs Quantum 5 hp engine model 124702. I understand the top screw should be set at 1.5 turns for carb. How about the bottom screw on the bowl also? Thanks again.

 
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cheese's Avatar
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07-09-07, 08:29 PM   #2  
I believe the top screw you're referring to is the idle speed screw, and there is no known setting for it. You set it to the desired idle speed with the engine running. It should not affect running. The screw just over the bowl is the air-fuel mixture screw and I'd set it at 1 1/2 to 2 turns out from lightly seated.

It does sound like you have carb problems. You might need to remove and clean it out well.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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07-10-07, 02:41 AM   #3  
Post back with the type and code numbers (going along with the model number you already posted) so I can provide you with the proper Briggs rebuild kit part number you'll likely need. This, along with some carburetor cleaner should have you back up and running well. Is the carburetor loose to the intake manifold, by any chance?

 
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07-12-07, 04:42 PM   #4  
Well, I took off carb and cleaned really well and still won't run. I can get it to run a little (few seconds) when I prime lots. Other than when I prime I really see no gas in carb. How much gas should I be seeing anyway without priming? There is plenty of gas in bowl so line from tank to bowl is ok and I have cleaned with whole can of carb cleaner and blown all holes with air which none appear to be clogged. Model is 124702, type 3106 and code 01 92101959. I have backed out each screw (2) on carb 1.5-2 times. Carb is tight with engine. Anything else I should be doing other than taking to shop or shopping for a new one? Would a carb kit do any good?

Thanks

 
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07-12-07, 06:53 PM   #5  
It sounds like you might have missed the small hole in the main jet. Look closely and use a fine wire to clean them out and respray with cleaner to flush.

 
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07-13-07, 03:32 AM   #6  
Does the intake manifold look OK? Is the o-ring seal in place between the carburetor and manifold in place? If your answer is YES to both questions and the trick that KID suggested yields no favorable results then I'd say that you have a carburetor that should be soaked in a good bath type cleaner (I like Napa # 6402) and reconditioned with a Briggs rebuild kit, part number 498260, or, if the condition of the caburetor dictates, replacing the carburetor. Most spray cleaners won't remove heavy varnish buildup and won't get to the internal fuel passageways well. By the way, you will see no fuel in the venturi (throat) if the carb is functioning properly.

 
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07-13-07, 06:06 AM   #7  
I agree, a good soaking is best. Did you use the can of cleaner ith the engine running or did you disassemble the carb and try to clean it witht he spray? I have had some luck with spray by spraying it in carb enough to get it to start and spray whenever it tried to die. Basically keeping it primed until the cleaner cleaned the varnish out of the passages. I have also used torch cleaners to clean passages out then soaked carbs. If you soak and blow out passages, protect your eyes!

 
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07-13-07, 12:26 PM   #8  
O ring is solid to engine and I did spray cleaner after taking carb off engine. Is there supposed to be an o ring of some sort where needle valve of carb float fits into bottom of carb? If so, I don't have one and that may be a problem? Just wondering if I am missing some small parts which may be a problem...I have the needle valve and float and hinge pin for the float. Are there some other loose parts that go along with float that I am missing?

 
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07-13-07, 01:12 PM   #9  
I think some have rubber seats and some may just have brass. If it has the rubber seat, you might take a screw of some kind and gently work it out by screwing the threads of the screw into ita little and pulling it out. Not really sure about a pushmower. Might dry the Sears part site and get a diagram of the carb.

 
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07-13-07, 05:52 PM   #10  
Wait. What's that I hear??? It is the roar of my lawnmower which now runs as sweet as country music. I got some 4 strand picture wire and took a strand off and ran through all the holes a few times and must have had some unseen dirt because now it runs great. Thanks a lot fellas.

 
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07-13-07, 08:19 PM   #11  
Good job. Thanks for the update!

Boman, is that you? (the same Boman that used to frequent these forums years ago)? If so, nice to see you again!


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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07-14-07, 03:54 AM   #12  
Posted By: cheese Good job. Thanks for the update!

Boman, is that you? (the same Boman that used to frequent these forums years ago)? If so, nice to see you again!
Guilty as charged. Good to see some of you guys still at it.

 
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07-14-07, 04:45 AM   #13  
By the way, I think it still might be beneficial to spray a few spurts of cleaner into carb while the engine is Running. Not enough to flood it out, just eneogh to make it rev higher a few times. Might help to clean any varnish from left over gas in the passages.

 
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